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Town Spotlight

Posted on: June 10, 2021

Chatham Water Department's Drinking Water Public Education

Pouring Water in Glass

On October 2, 2020, the Massachusetts Department of Environmental Protection (MassDEP) promulgated a new drinking water regulation and Maximum Contaminant Level (MCL) of 20 nanograms per liter (ng/L) for the sum of six per- and polyfluoroalkyl substances (called PFAS6). April 2021, under the new regulations, the required samples taken by the Chatham Water Department confirmed elevated levels of PFAS6 in one well producing drinking water. Even though the level is above the MCL, a PFAS6 MCL violation has not occurred, as violations are based on three months of testing. Instead, we are required to provide you with this information to make you aware of the elevated levels observed and what is being done so you can make informed decisions about your drinking water while we take corrective action(s) and continue to monitor the water supply.

The Chatham Water Department has not violated the drinking water regulations. A PFAS6 MCL violation occurs when the average of all monthly samples collected over a quarter exceeds the MCL. If our system had violated the PFAS6 MCL, our system would have issued a PUBLIC NOTICE. The most recent PFAS6 sampling results for our water supply are shown below:

Supply Well (well #)LocationInitial Sample (ng/L) 4/21/2021Re-sample (ng/L) 4/29/2021Average (ng/L)
1South ChathamND*na
2South ChathamND*na
3South ChathamND*na
4Indian Hill12.610.811.7
5Training Field28.740.734.7
6Tirrell's WayND*na
7Eben's WayND*na 
8Training Way8.947.298.1
9Town ForestND*na

ND = Non-detect.

* wells with initial non-detect are not required to re-sample.

ng/L = nanograms per liter, equal to parts per trillion.

Well 5, where elevated levels PFAS6 were reported, is one of 9 sources that supplies drinking water to our system. PFAS6 levels were reported below the 20 ng/L MCL at all other locations. Upon receiving the results identified above, the Water Department took Well 5 (05G) offline and it remains so at the time of this mailing. Six Wells were non-detect and two wells were below the MCL of 20 ng/L.

What is PFAS6?

PFAS6 includes perfluorooctanoic acid (PFOA), perfluorooctane sulfonic acid (PFOS), perfluorononanoic acid (PFNA), perfluorohexanesulfonic acid (PFHxS), perfluorodecanoic acid (PFDA) and perfluoroheptanoic acid (PFHpA). PFAS are man-made chemicals that have been used in the manufacturing of certain fire-fighting foams, moisture and stain resistant products, and other industrial processes. For more information see the weblinks listed below or the Water Department website.

Some people who drink water containing PFAS6 in excess of the MCL may experience certain adverse effects. These could include effects on the liver, blood, immune system, thyroid, and fetal development. These PFAS6 may also elevate the risk of certain cancers. For more information on PFAS, see the links below.

What should I do?

For Consumers in a sensitive subgroup (pregnant or nursing women, infants, and people diagnosed by their health care provider to have a compromised immune syste

  • Consumers in a sensitive subgroup are advised not to consume, drink, or cook with water when the level of PFAS6 is above 20 ng/L.
  • Consumers in sensitive subgroups are advised to use bottled water for drinking and cooking of foods that absorb water (like pasta
  • For infant formula, use bottled water or use formula that does not require adding water.
  • Bottled water should only be used if it has been tested. A list of companies that voluntarily tested their water for PFAS and shared the results can be found on MassDEP’s website at: https://www.mass.gov/doc/bottled-water-tested-for-pfa

For all other consumers not in a sensitive subgroup

  • If you are not in a sensitive subgroup, you may continue to consume the water because the 20 ng/L value is applicable to a lifetime consuming the water and shorter duration exposures present less risk
  • If you have specific health concerns regarding your past exposure, you should see the Centers for Disease Control and Prevention’s link below and consult a health professional, such as your doctor.

Steps you can take to reduce your intake

Consider taking the following steps while actions are being implemented to address this issue:

  • For older children and adults (not in a sensitive subgroup), the 20 ng/L value is applicable to a lifetime of consuming the water. For these groups, shorter duration exposures present less risk. However, if you are concerned about your exposure while steps are being taken to assess and lower the PFAS6 concentration in the drinking water, use of bottled water will reduce your exposure.
  • Home water treatment systems that are certified to remove PFAS by an independent testing group such as NSF, UL, or the Water Quality Association may be effective in treating the water. These may include point of entry systems (POE), which treat all the water entering a home, or point of use devices (POU), which treat water where it is used, such as at a faucet. While some systems have been shown to meet EPA’s higher standard of 70 ng/l for two PFAS compounds (PFOA & PFOS), to date none have demonstrated they can meet MassDEP’s lower standard of 20 ng/l for the six compounds that make up PFAS6. For information on selecting home treatment devices that are effective in treating the water for PFAS6 follow the weblinks below or visit the Water Department website at www.chatham-ma.gov/water-sewer-division.
  • In most situations, the water can be safely used for washing foods, brushing teeth, bathing, and showering.

Please note: Boiling the water will not destroy PFAS6 and will somewhat increase its level due to evaporation of some of the water.

What is being done?

The Water Department has taken the following proactive measures:

While Well 5 remains offline, the Department is investigating alternative sources to meet increased summer demand for water. The Town issued mandatory water conservation measures, including odd/even watering days, restriction on time-of-day watering, etc., as measures to reduce pumping. As conservation measures alone may fail to reduce demand such that Well 5 can remain offline, the Department is investigating blending water from Well 5 with Well 8 to produce a combined water below the MCL. The Department is also investigating emergency equipment that could remove the PFAS6, and potentially obtaining water from Harwich or bringing Well 4 online after testing - while a permanent solution is sought.

Where can I get more information?

For more information, please contact Tom Barr at 508-945-5150. See also the web links listed below or visit the Chatham Water Department website.

This public education material is being sent to you by: Chatham Water Department. PWS ID#: 4055000 Date distributed: 6/16/2021

Please share this information with other people who drink this water, especially those who may not have received this notice directly (for example, people in apartments, nursing homes, schools, and businesses).

View the full Document (PDF)


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